FirebaseInstanceID Framework Reference

InstanceID

classInstanceID:NSObject

Instance ID provides a unique identifier for each app instance and a mechanism
to authenticate and authorize actions (for example, sending an FCM message).

Once an InstanceID is generated, the library periodically sends information about the
application and the device where it’s running to the Firebase backend. To stop this. see
[FIRInstanceID deleteIDWithHandler:].

Instance ID is long lived but, may be reset if the device is not used for
a long time or the Instance ID service detects a problem.
If Instance ID is reset, the app will be notified via
kFIRInstanceIDTokenRefreshNotification.

If the Instance ID has become invalid, the app can request a new one and
send it to the app server.
To prove ownership of Instance ID and to allow servers to access data or
services associated with the app, call
[FIRInstanceID tokenWithAuthorizedEntity:scope:options:handler].

Declaration

Return Value

Returns a result of app instance identifier InstanceID and a Firebase Messaging scoped token.
param handler The callback handler invoked when an app instanceID and a default token
are generated and returned. If instanceID and token fetching fail for some
reason the callback is invoked with nil result and the appropriate error.

Declaration

Returns a token that authorizes an Entity (example: cloud service) to perform
an action on behalf of the application identified by Instance ID.

This is similar to an OAuth2 token except, it applies to the
application instance instead of a user.

This is an asynchronous call. If the token fetching fails for some reason
we invoke the completion callback with nil token and the appropriate
error.

This generates an Instance ID if it does not exist yet, which starts periodically sending
information to the Firebase backend (see [FIRInstanceID getIDWithHandler:]).

Note, you can only have one token or deleteToken call for a given
authorizedEntity and scope at any point of time. Making another such call with the
same authorizedEntity and scope before the last one finishes will result in an
error with code OperationInProgress.